1. Field of the Invention
The invention relates to methods and apparatus for cleaning or carding textile fibers between a rotating cleaning or carding drum having clothing thereon and carding elements which surround the drum and also have clothing. It is concerned particularly with the interaction of the clothing teeth carried by the relatively movable components and the effects produced thereby on the quality of the fibers.
2. Description of the Related Art
The developments which have taken place in cleaning and carding machines used in the cotton spinning industry and carding have continued to seek increases in quantity of output without sacrificing yarn quality. The requirements with respect to the uniformity and cleanliness of card slivers and with respect to yarn strength have remained unchanged or even increased.
However, increases in machine output could ordinarily be expected to be accompanied by a certain amount of fiber deterioration, because of an increase in fiber treatment severity. An increase in output makes it necessary to increase the speed of the working drums (e.g. the cleaning drum in a fine cleaning machine and the speed of the swift in a card) which have toothed clothing for gripping the tufts from the upstream feed elements and cleaning and parallelizing the fibers through additional opening and carding.
Some efforts have been made to cultivate cotton species which are better adapted to modern requirements. However, the increase in machine output capability has been much more rapid than the change in the product to be processed.
In other words, the randomly oriented fibers in the fiber tufts have to be parallelized faster now by the tips of conventional clothing. Without additional steps, this would result in increased damage to the staple. The desire, however, in the cleaning and carding of fibers is towards speeding up operation without actually increasing the damage to the staple.
As is also known, the requirements on the end product, i.e. the yarn, depend on the subsequent processing, and consequently it must be possible so to choose the mixtures of cotton in the blowroom that the intensity of working is with advantage, variable during subsequent processing after the bales have been opened, i.e. during cleaning and carding.
In Swiss application number 04103/88-3 (corresponding to U.S. patent application Ser. No. 07/430,164), the owner of the present invention has already proposed steps in this direction for adapting the intensity of cleaning on the card. In another Swiss application number 02312/89-9 (U.S. patent application Ser. No. 07/540,777), the disclosure of which is incorporated herein by reference, there is shown and described the possibility of varying the intensity of carding by varying the aggressiveness of the clothing on carding elements disposed around the carding drum.
Another commonly owned Swiss application No. 1929/89-1 (corresponding to U.S. patent application Ser. No. 07/524,744) relates to a method of optimizing the processing of cotton in a spinning mill as regards throughput.
Accordingly, steps have already been proposed for adapting to changing end product requirements, i.e. changing yarn requirements, and the possibility of obtaining various feeds by altering the mixture.
Another factor is that the difficulty of converting fibers from random orientation, e.g. in a tuft, to parallel orientation increases with the speed at which the change in orientation is carried out, because rapid engagement (e.g. of clothing in random orientation) is more likely to result in neps than is slow engagement.
It is desirable, therefore, that the interaction between clothing on a rotating drum co-operating with clothing on carding elements be such that the fiber orientation can be altered at high speed with substantial avoidance of neps and damage to the fiber. One practical though not completely relevant example explaining the foregoing is the process of untangling string manually using the fingers, something which of course can be achieved only by careful and considered action, whereas a tangle abruptly torn apart will result in a number of individual tangles which are impossible or much more difficult to unravel.